We use a fixed positional encoding to equip the model with time sequence information. The positional encoding [1]} is calculated for the time step \(T\)  and city \(C\)  axes according to the Eq. (REF ), where \(C\)  is the length of the city axis, \(pos\)  is the position in time step axis and \(i\)  is the position in the city axis. We broadcast the values along the weather variables axis \(F\) . Hence, the values of the positional encoding are identical across the axis \(F\) , and differ in \(T\)  and \(C\)  axes.
\( {\left\lbrace \begin{array}{ll}PE_{(pos,2i)}= \sin (pos/10000^{2i/C}), \\PE_{(pos,2i+1)}= \cos (pos/10000^{2i/C}).\end{array}\right.}\) 
